Technical Field of the Invention
This invention generally relates to the field of protective coatings for fluid storage vessels. In particular, the present invention is directed to a protective coating for the surfaces of a storage container to protect the container against molten sulfur and sulfuric acid.
Description of the Related Art
Severe deterioration of concrete, which is caused by the conversion of oxides of sulfur to sulfuric acid in the presence of moisture, has been noticed in the sulfur pits, sulfur tanks and sulfuric acid containers in petroleum refineries, and gas plants particularly in those where the groundwater table is very shallow. The high temperature of the molten sulfur and the formation of sulfuric acid in the presence of moisture lead to cracking and spalling of concrete. The repair of cracks by epoxy injection is not feasible because of the elevated temperature of the walls of the sulfur pits/tanks. Similarly, the commonly available protective coatings do not withstand the exposure conditions in the sulfur pits. The deteriorated concrete is generally prepared with ordinary Portland cement concrete or silica fume cement concrete. However, these two materials exhibit deterioration within a short period of time.
There is a growing concern regarding the emission of H2S gas and the related health and environmental hazards in the plants. From the environmental and structural perspectives, there is a need to develop a protection system for concrete against the aggressive sulfur and/or acid attack.